Sunday, September 21, 2014

Fabulous first week of fall ahead!

Great harvesting weather is expected this weekacross southern MB with dry and warm conditions(photo by Shawn Dziuk near Glen Ullin, ND)

After a gloomy and occasionally damp weekend, the weather pattern will be turning decidedly warmer and drier across southern Manitoba this week as an upper ridge of high pressure builds across the Prairies. The result will be a fabulous stretch of dry and warmer than normal weather over the upcoming week with temperatures climbing into the mid 20s at times, and possibly even upper 20s by late week. This will be welcome news for farmers trying to harvest this year's crop, and just in general for any outdoor activities. Fall officially arrives Monday evening (Sept 22nd), but fall-like weather will be delayed for awhile as we get a nice last taste of summer-like weather this week. Officially, Winnipeg has yet to record its freeze of the season yet, with a minimum temperature so far this month of +1.1C at YWG airport (Sept 12th) On average, Winnipeg usually records its first freeze of the season by Sept 22nd, so the growing season will be extended a bit longer than normal this year. After this past winter's bitter cold and slow start to spring, we deserve it! Enjoy!

Not yet.. at least for Winnipeg. GFS and Canadian CEPS ensemble output both giving 28C for Winnipeg Friday at this point, but depending on how strong this upper ridge is, things could be a couple of degrees warmer (or cooler) Western RRV, SW MB and downslope areas from Riding Mtns (Dauphin/McCreary) would have a better shot at 30C Friday. We'll see. Won't complain with upper 20s though! Note that record high for Friday is 31.7C (1952) Latest 30C reading on record in Winnipeg is Oct 6 (1879).

Glorious day with an over-achieving high of 26.5C in Winnipeg today thanks to a SW downslope wind and brilliant sunshine that boosted temps a couple degrees higher than expected. We lose the downslope tomorrow with a straight southerly wind, but still nice and warm with highs near 26C. Similar temps Wednesday, then Thursday and Friday have 30C potential even for Winnipeg as a surge of even warmer air moves in. NAM showing 90F (32C) temps over western RRV Thursday, and 29C for Winnipeg. Love it!

An aggressive high of 33C forecast for Winnipeg Thursday.. while most guidance is supporting about 29C or so for the city. 30+ temps more likely over western RRV and west slopes of Riding Mtns (Dauphin/McCreary) with warmer air aloft and some downsloping off higher terrain to the west. Still a toasty day.. but 33C for Winnipeg seems a bit overdone.

Winds are gusty today (gusting to 50 km/h) but will lighten up tomorrow. Southerly winds pick up again Thursday and Friday to about 30 km/h, with gusts to 50 again. Breezy, but not as windy as we sometimes see in these warm southerly flows.

Extensive area of low cloud spread over ND/MN spread northward into southern MB overnight into early this morning, and will stick around through the morning before gradually breaking up this afternoon. Speed of clearing today will dictate today's highs.. look for highs around 20C where skies are slow to clear.. and 25C where sun comes out sooner. Sunnier Thursday and Friday with highs near 30C for Winnipeg.. 30C+ possible over western RRV and downslope areas.

Low cloud has been slow to clear out of RRV and SE MB.. but has cleared out nicely this afternoon over western MB into the western RRV allowing temps to rise to 27C near the SK border, while we struggled to the 20C mark under the cloud. We should continue to see some clearing for Winnipeg this evening.. but low cloud may return tonight as SSE flow picks up again. That may keep us with low cloud and some fog patches into early Thursday morning before skies clear out. Temps tomorrow with southerly winds and sunshine should reach the upper 20s in Winnipeg by Thursday afternoon, with 30C+ temps over western RRV and western MB.

Interesting situation this morning with low cloud to the west and east of Winnipeg/RRV.. but a narrow clear wedge up the valley. Try to predict that 24 hours in advance! Low cloud still hanging on east of the RRV with a thin sliver over western RRV late this morning, but that should burn off quickly this afternoon. Then it's a question of how warm it will get. Warmest air aloft, best solar and some downsloping winds will give parts of SW MB hot spot honours today with highs of 33C likely in downslope areas off the Riding Mtns (Dauphin/McCreary) and Turtle Mtn (Boissevain, etc) as well as localities near the SK border (Pierson, Reston, etc) Note temps of 28-29C already as of 11 am in the Boissevain-Killarney area thanks to downsloping winds off the Turtle Mtns. Winnipeg has an outside shot at 30C, but that gusty south wind up the valley and some lingering cooler air from the stratus/fog deck will likely keep us shy of hitting the 30 mark, but 27-28C certainly possible. No complaints here!

Usually it is. A high dewpoint means there's more moisture in the air. As the sun heats the airmass during the day, some of the solar energy goes into evaporating that extra moisture instead of heating up the air itself. As a result, the air doesn't warm up as quickly or as much as a drier airmass. Of course, you can have a hot and humid airmass.. but in order to maximize your highest temperature potential.. you need lower dewpoints. A dry surface helps as well. (i.e. dry soil conditions vs wet) This is likely one reason to explain why we (southern MB) don't get as many extreme temperatures (35C+) as we used to. We've had a wetter, more humid climate for a while now (25 years or so)

Unbelievable warmth in western Manitoba. By 3 PM, Dauphin had 33.3 C, and both Brandon and Minnedosa had hit 33.5 C! I don't know about the other two but Brandon has already smashed its record temperature for today.

That moist SSE flow will persist through tomorrow. Trough to the west bring in SW flow and better mixing washes out. NAM hints at better mixing moving in early this evening before flow turns SSE all the way up to 925 hPa. The models also depict higher RH values at 925 hPa moving in from NW Minnesota. Therefore potential exists for more fog and stratus formation overnight which would have to burn off tomorrow.

Unfortunately NAM shows cold front moving through around midday Saturday.. ruining a potentially summer like day. Looks like once again Grand Forks/ Fargo will bask in warmer air mass for a good part of the weekend. Good area of midlevel forcing/ deformation behind the front for rain on Sunday..

Didn't set a record high today in Winnipeg (max of 27.7C, record 31.1C in 1950) but we did set a record for highest dewpoint for Sept 25th (17.6C) Felt tropical out there today. Balmy south breeze tonight will keep temperatures up with an overnight low of only 16C or so.. which would be a record high minimum for Sept 26th if it holds through midnight Friday. (current record high minimum for Sept 26th is 14.4C in 1950.)

By the way, today's high of 27.7C was the warmest day of Sept so far in Winnipeg and we should be at least as warm as that tomorrow, or warmer by a degree or so. It will be quite windy though with gusty south winds to 60 km/h or even higher along with dewpoints in the upper teens again. Another tropical day on tap in southern Manitoba!